Process and device for shaking the forming wire of fourdrinier machines



Jan. 18, 1955 PROCESS E. w. BREUNING ET AL 2,699,709

AND DEVICE FOR SHAKING THE FORMING WIRE OF FOURDRIMIER MACHINES 2Sheets-Sheet 1.

Filed June 6, 1951 llllllllllllfllllllllllll FIG-4IlllllllllllllllllllllllIi llllllllllllllllllllllillIllllllIlIllllllllllllll Illlllllllllllllllllll INVENTORfi ERNST W,BREUNING HANS J. KARPINSKI HEINRICH O. MORIKE ATTORNEYS Jan. 18, 1955 E.w. BREUNING ET AL 2,699,709

PROCESS AND DEVICE FOR SHAKING THE FORMING WIRE OF FOURDRIMIER MACHINESFiled June 6, 1951 2 Sheets-Sheet 2 Frq .7 T Q;

, INVENTORS ERNST I? BKEUNING EMVJ J KHFPINSK! HEINRICH 0. MOEZKEATTORNEYS cloth is moved United States Patent PROCESS AND DEVICE FORSHAKING THE FORM- IN G WIRE 0F FOURDRINIER MACHINES Ernst WilhelmBreuning, Albeck, and Hans Johann Karpinski and Heinrich Otto Milrike,()berlenningen, Germany, assignors to Papierfabrik Scheufelen,Oberlenningen, Germany Application June 6, 1951, Serial No. 230,243

9 Claims. (or. 92-45 The present invention relates to paper machineryand, more particularly, to the dewatering of paper stock on the wirecloth and to the shaking of the wire cloth.

For all types of fibre stock webs, in particular for paper stockproduced by dewatering on the wire cloth out of a suspension of thefibre in a watery vehicle, the character of felting during thedewatering process is of primary importance both for the appearance(look-through) and for the strength of the web (length of fracture).

The more uniform the felting is, the more uniform is the look-throughand hencethe appearance and also the higher is the strength.

During the dewatering process on high speed wire cloths the fibres tendto lay themselves in the direction of the wire in motion (parallel toone another), which results in an undesired increased strength in thelengthwise direction at the expense of the strength in the transversedirection.

For the purpose of counteracting this undesired phenomenon a number ofvariegated devices and processes have been applied, which, in the main,have the purpose to impart a shake or a vortex motion to the suspensionof fibres during the time of dewatering with a view to prevent theparallel disposition of the fibres and to obtain a more uniformdistribution of the lengthwise and transverse strengths.

All known devices of this type make use of the principle providing forshaking of the wire cloth. The wire by one or several wire rolls, ortable rolls, to which a shaking motion is imparted.

As a resut of this, not only the rolls but also the bearings and theadjoining wire cloth frame parts are subjected to these motions, so thatnot only the comparatively light wire cloth'is caused to vibrate, butalso large masses of metal, which fact results in excessive Wear andtear of the bearings, higher power requirements, etc. The r large masseswhich must be moved preclude attaining the higher oscillationfrequencies which would be desirable, but, furthermore, the direction ofthe vibrations with all known devices is, for reasons of design, neithereasily adjustable nor can it be selected at will.

The new process of this invention avoids these known drawbacks byproviding for an electrical current, which is sent through the wirecloth, which is moved by the action of a magnetic'field directedcrosswise to the direction of the running wire cloth. Hence, the wirecloth is not moved and shaken, respectively, as a result of the movementof a large mass, but rather by the direct movement of electro-dynamicforces. The magnetic field is preferably of the D. C. magnet type, whilea pulsating electric current, such as A. C., is used as electricalcurrent passing through the wire. The magnetic field may also bepulsating, such as an A. C. field, while D. C. or A. C. of any wave formmay be used for the wire cloth of the paper machine. The amount of thewire shake can be adjusted by adjustment of the field intensity of themagnet or of the electrical current in the paper machine wire cloth, orboth, while the duration of the wire shake can be adjusted by adjustmentof the exciting current frequency and/ or of the ratio:

Exciting current frequency Natural frequency of the wire or parts ofsame changing the direction of the axes of the magnetic field and/ orthe ratio:

Exciting current frequency Natural frequency of the wire or parts ofsame The wire cloth may also be shaken according to one of thewell-known mechanical methods, while being subject to a simultaneouselectro-dynamic shaking movement, which combination substantiallyimproves on the drawbacks of the known methods.

The drawings show applications of the manufacture of paper. box 1, thepulp 2 is fed onto cloth 3, as shown in Figure over the two rolls 4 and5. A. C. is supplied to the-two rolls 4 and 5, isolated from each other,via contact devices ti and 7 by the transformer =3. The part of wirecloth 3, which conveys the paper stock, runs between the two magneticpoles or electro-magnetic members, 9 and it) of an electromagnet, whichby the action of a field winding 11 between its pole shoes 9 and it)produces a magnetic field 12 extending through the paper machine wirecloth 3. i

in the wire 3, the warp wires of which, in a magnetic field, representconductors through which electrical current flows, electro-dynamicforces are set up, which impart transverse vibrations such as shown bythe arrows in Figure 1 depending on the magnetic field intensity, theintensity of the A. C. and the frequency.

In Figure 2 the field winding 11a is not arranged at one side of thewire cloth only, but extends over the whole width of the wire cloth. Thewinding Ila is wound about the center portion of an electromagneticmember so as to form the poles 9 and it. Underneath the wire cloth ironparts 13 are arranged without any windings, which iron parts completethe magnetic circuit with the poles 9 and 10. With this arrangement thesuccessive magnetic fields 12a and 1215 through which the wire clothpasses change direction, so that the warp wires are imparted an S-shapeddeflection. instead of one single long exciter coil smaller separatecoil units may be provided.

The distribution of the current in the paper machine wire cloth can becontrolled and varied at will by well known methods, e. g. it may bedesired to provide for the possibility that in such parts of the papermachine wire cloth as do not play a role in the process-this applies inparticular to tr e lower part of the wire cloth-no electrical currentflows or a current that is smaller than that flowing in the upper part,in particular over the action range of the magnetic field.

Figure 3 shows an example of such an arrangement. Besides the maintransformer, which feeds an electrical current via brushes into the tworolls and the paper machine wire cloth, a skin eifect type transformer13 is provided through the core opening of which the bottom wire clothpart is let. This transformer generates in the bottom wire cloth part avoltage which counteracts the voltage drop in the paper machine wirecloth, which suppresses the electrical current in the bottom partof thepaper machine wire cloth. The upper reach of the wire cloth in Figure 3is, of course, traversed by a magnetic field as is shown in Figures 1and 2.

Figure 4 shows a unit combing the main transformer and the skin effecttype transformer. The bottom part of the wire cloth 3 and the feed-wire33 or" the brushes pass through the core opening of the transformer 18a.The wire cloth 3, along the lower reach thereof, as a result of thebetter conductivity of the connection wire 33, carries no current, whilecurrent does flow in the upper reach of the wire cloth and the upperreach, as before, is traversed by a magnetic field.

Figure 5 shows another example for the application of the invention,which does not require any feed-wire to carry electrical current via therolls to the paper machine wire cloth, since the electrical current inthe paper machine wire cloth is generated directly thereon by induction.The magnet system may be designed similar to that of an induction motorwith a moving field being established by coils 21, 22 and 23 on ironframe 24 with another iron part 25 beneath the wire cloth.

this invention for In Figure 1 from the head the wire cloth 3. The wire1, moves from left to right In this arrangement, the periodic reversalof the exciting currents sets up a moving field and a vibrating movementis imparted to the wire cloth.

In Figure 6, legs 36, 39 and 40 of the magnetic frame 41 set up aspatially fixed magnetic field 'upon energization of the respectivecoils thereon, while varying of the exciting currents for the coilsinduces currents in the paper machine wire cloth which react with thefield to set up vibration creating forces in the wire cloth.

Figure 7 is a plan view of Figure 5.

When using the transmission by induction it may be advisable to useintermittent impulses, in which case the frequency of the electricalcurrents need not be correlated with the mechanical frequency of thewire shake.

What we claim is:

l. The method of dewatering paper stock during the manufacture of papercomprising; supporting an endless wire cloth on spaced rollers andmoving the wire cloth, flowing the stock onto the wire cloth,establishing an electrical current in the wire cloth by creating apotential difference between said rollers, establishing a magnetic fieldthrough the wire cloth and substantially normal to the plane of the wirecloth, establishing an electromotive force in the lower reach of saidwire cloth which is opposite to the potential difference between saidrollers and of about the same algebraic value, whereby substantially nocurrent will flow in the lower reach of the wire cloth due to thepotential difference between said rollers.

2. A paper machine having a moving endless wire cloth to receive fibrouspaper stock and through which the paper stock drains, means forestablishing a pulsating electric current in the warp wires of the upperreach of said wire cloth, means for establishing a magnetic fieldthrough and substantially normal to said wire cloth to transverselyoscillate said wire cloth comprising electromagnetic members disposedabove and below the upper reach of said wire cloth, and means forselectively controlling said current to vary the amplitude of saidtransverse oscillations in said wire cloth.

3. A device as described in claim 2 in which the means for establishingthe magnetic field is U-shaped, with the legs of the said U arranged onopposite sides of the wire cloth and parallel thereto.

4. A device as set forth in claim 2 in which the means for establishingthe magnetic field consist of an electrically excited magnet on one sideof the wire cloth having two poles and a magnetic member on the otherside of the wire cloth completing the magnetic circuit between the twopoles whereby the magnetic field is in two parts, respectively, reversedin direction and substantially normal to the plane of the wire cloth.

5. A paper machine having an endless moving conductive wire cloth toreceive paper stock to drain therethrough, means for establishing amagnetic field through and substantially normal to the wire cloth in theupper reach thereof, spaced electrically conductive rollers supportingsaid endless wire cloth, a transformer having the terminals of itssecondary side connected with said rollers to create a potentialdifference therebetween, and a transformer core encircling the lowerreach of said wire cloth and having a primary coil whereby a voltage inthe lower reach of the wire cloth can be established to counteract thevoltage drop in the upper reach of the wire cloth thereby suppressingthe current flow in the lower reach.

6. A paper machine having a moving endless wire cloth to receive fibrouspaper stock and through which the paper stock drains, means for inducingan alternating current in the wire cloth comprising a primarytransformer, a coil and a transformer core opening extending throughsaid primary coil and around a portion of one reach of said wire cloth,means for establishing a magnetic field through and substantially normalto said wire cloth to transversely oscillate said wire coth andcomprising electro-magnetic members disposed above and below the upperreach of said wire cloth, and means for selectively controlling saidcurrent to vary the amplitude of said transverse oscillations in saidwire cloth.

7. In the method of dewatering paper stock by transversely oscillating amoving endless Wire cloth, the steps of flowing the stock onto themoving wire cloth, establishing a pulsating electric current in the warpwires of the wire cloth, establishing at least two magnetic fieldsthrough and substantially normal to the upper reach of the wire clothand spaced longitudinally on said wire cloth, said magnetic fields beingreversed in respect to each other thereby transversely oscillating thewire cloth, and controlling the current to vary the amplitude of thetransverse oscillations of the wire cloth.

8. In the method of dewatering. paper stock by transversely oscillatinga moving endless wire cloth, the steps of flowing the stock onto themoving wire cloth, establishing an alternating electric current in thewarp wires of the wire cloth, passing the moving wire cloth between themagnetic poles of an electro-rnagnet to set up a mag netic field throughand substantially normal to the wire cloth thereby transverselyoscillating the wire cloth, and controlling the alternating electriccurrent to vary the chagacteristics of the transverse oscillations ofthe wire c of 9. The method of transversely oscillating the movingendless wire cloth in a paper machine which comprises establishing analternating electric current in the wire cloth in the upper reachthereof, establishing a magnetic field through a portion of said upperreach and in a direction normal to the plane of the wire cloth totransversely oscillate the wire cloth, controlling one of said currentsand magnetic field to vary the characteristics of the transverseoscillations, and mechanically oscillating the wire cloth in addition tothe aforementioned oscillations and selecting the frequency of variationof the current and field so that the vibration of the wire cloth createdthereby differs in frequency from the natural mechanical frequency ofthe said wire cloth.

References Cited in the file of this patent UNITED STATES PATENTS958,181 Schloemilch May 17, 1910 1,958,696 Digby May 15, 1934 2,076,991Holgersson et al. Apr. 13, 1937 2,338,904 Cowles Jan. 11, 1944 2,435,487Adler Feb. 3, 1948 2,562,545 Gogolick July 31, 1951 FOREIGN PATENTS I501,257 Germany ..4 July 5, 1930

